US1618497A - Welding transformer - Google Patents

Description

Feb. 22 1927.

C. B. WATERS WELDING TRANSFORMER Filed Feb. 4. 1924 TIlll ill! INVEN TOR.

ATTORNEY.

Patented Feb. 22, 1927.

UNITED STATES PATENT OFFICE.

wnnnme rmsronm lpplication filed February 4, 1924. Serial No. 680,489.

The present invention relates to are welding transformers.

More particularly the invention relates to improvements in welding transformers with exaggerated magnetic leakage whereby greatly improved welding characteristics are attained.

The improvement is in general affected by superimposing on the main secondary voltage and current waves, voltage and current waves which may be varied in magnitude and phase relation with respect to the main secondary waves in accordance with the work to be welded and the personal equation of the operator.

It frequently is desirable to preheat work before welding, or to modify the operation of the welder in a manner to produce a heating effect together with a limited arc welding effect. Such operations as the repair ing of scored cylinder walls by depositing metal in. the scored parts, for example, can in this manner be successfully and cheaply carried out. Heretofore no'arc welder has been produced in which these characteristics may be secured at will.

An object of the present invention is to provide an improved form of arc welding machine for ordinary welding operations.

Another object of the invention is to provide a welder in which the operation may be modified to simply preheat the work, or to produce a limited heating and a lirnlted arc eifect, or to produce a full arc' effect with substantially no heating of the work except at the arc craters as is usual in ordinary arc welding. Still other objects of the invention will appear in the following disclosure of the preferred embodiments of the invention of which 4 Figure 1 is a diagrammatic representation of a form of apparatus in which a split primary winding and a single secondary winding is utilize Figure 2 is a diagrammatic representatlon of an embodiment of the invention in which a transformer with'split primary and split secondary windings are utilized.

Figure 3 is a diagrammatic representation of an embodiment of the invention in which a split primary and a split secondary together with an auxiliary secondary w nding on magnetic shunt are preferably utihzed.

Figure 51 is a diagrammatic representatlon of an embodiment of the invention in which an auxiliary transformer is utilized.

Referring to Fig. 1 a closed magnetic core comprised of yokes 1 and 2 and legs 3 and 4 is provided. A primary winding 5 is wound upon leg 3 and is connected by means of conductors 6 and 7 and switch 8 to a suitable source of alternating current. A secondary winding 9 is applied on leg 4 and is connected by means of conductors 10 and 11, and switch 12 to a metallic arc welding electrode 13 and a piece of work 14 to be welded. lVound upon leg 4, in close proximity to winding 9, is an auxiliary primary winding 15 which is connected by means of conduc tors 16 and 17 through switch 18, double pole double throw reversing switch 19 and variable inductance 20, in shunt to the main primary coil 5. j

In ordinary arc welding operations the various switches are adjusted to suit the particular requirements of thework to be welded, switch 19 being closed in a manner to add the voltage induced by winding 15 in the winding 9 to the voltage induced in coil 9 by the primary winding 5. The relative phase of the voltages in the secondary is. adjusted by means of adjustable reactance 20.

When it is desired to preheat before welding switch 19 is closed in a manner to oppose the voltages induced in coil 9 by windings 5 and 15, and the various switches are adjusted so that no arc will be produced on separation. of the electrode from the'work. By aproper adjustment of reactance 20, the

phase relations may be shifted in a manner I to kill the are entirely. If a modified arc and heating effect is desired, the phase relations and voltage relations may be shifted by adjustment of reactance 20 and thevarious taps until the modification best suited for the work to be done is attained. It will l wavelwhich is suflicient to keep the arc going as the current induced by winding in the secondary goes through zero. Winding 9 performs the function of regulating the arc, and tends to maintain a constant current in the secondary circuit as in the well known Thomson arc transformers. The demands on the regulatin action of winding 9 are materially lessenedhbecause of the super-imposed voltage due to coil in keeping the are going over the zero current portions of the secondary current waves, and greatly in] )roved welding characteristics result.

n Fig. 2, a form is shown in which the form shown in Fig. 1 is modified by the addition of a winding 21 laced on leg 3 and connected in series in t 1e secondary circuit so that the voltages induced therein will add to the voltages induced in coil 9. The operation is substantially the same as set forth for Fig. 1, like parts having been designated by the same numerals. The action of coil 21 further improves the welding characteristics of the transformer.

In Fig. 3, the invention is shown as applied to an arc welding transformer of the type disclosed in Patent No. 1,464,145, issued August 7, 1923. In this form the modification shown in Fig. 2 is further modified by the addition of a central magnetic shunt leg 22 upon which a winding 23 is applied.

' Winding 23 acts as an automatic regulator winding andis connected in a manner to add the voltage induced therein to the open circuit secondary volta e. The operation of the machine as described in the above mentioned patent is improved by the action of winding 15 in the manner explained above.

In Fig. 4 a different method of applying the same principle is disclosed. Winding 15 of Fig. 1 is removed and an auxiliary transformer is utilized to produce a similar effect, on the secondary circuit. A .core 24 has wound upon one leg thereof an auxiliary primary winding 25 which is connected in shunt to the main rimar windin 5 b means of switch 26 and conductors 27 and 28. A winding 29 is applied to the other leg of core 29 and is connected to electrode 13 and work 14 by means of conductors 30 and 31 and double pole double throw reversing switch 32.

In operation the leakage reactance of the main transformer difi'ers materially from the leakage reactance of the auxiliary transformer. The result is that the voltages applied across the are are out of phase, as is the case in the other forms disclosed. The winding 29 also exerts a regulating influence on the are as is the case with winding 9. As in the forms above described, the transformer may be used for preheating before the arc is established.

It will be understood that. relative phase displacement may be caused by the use of capacity as well as inductance and the term lgreililctance in the claims means either or ot It will be further understood that many modifications of the invention will suggest themselves to those skilled in the art, and that the invention is not limited to the forms disclosed, but is limited in scope b the terms of the a pended claims only. I aving described preterred embodiments of the invention what is desired to be secured by Letters Patent and-claimed as new is:

1. The method of arc welding which comprises the steps of applying the resultant of a plurality of voltages displaced in phase with relation to each other, across an electrode and the work to be welded to estab lish a weldin arc, and varying the phase displacement oi the voltages to vary the relative energy consumed in the arc and in the resistance heating effect in the work to be welded whereby preheating of the work to be welded by the resistance heating effect may be eil'ected.

2. The method of preheating and are welding which comprises the ste s of applying a resultant of a plurality of a ternating voltages in such phase relation across a metallic electrode and the work to be welded that the electrical energy is to a large extent dissipated in resistance losses at the point to be welded and preheating the work, and after the work is reheated shifting the phase relations of the voltages so that the electrical energy is to a large extent dissipated in maintaining-a welding are between the electrode and the work.

3. A welding circuit comprising a metallic electrode, work to be welded, means for applying the resultant of a plurality of alternating voltages displaced 1n phase with relation to each other across the electrode and the work, and means for varying the phase angle between said voltages to vary the relative amount of energy dissipated in the arc and in resistance losses.

4. Arc welding apparatus comprisim a closed magnetic core; a secondary win ing on one part of the core; a plurality of primary windings on said core connected to a common primary source of energy; and a variable inductance interposed between one of said primary windings and said source.

5. The apparatus as set forth in claim 4 together with means for reversing the connections of one of said primary windings to said source.

6. The apparatus as set forth in claim 4 in which the secondary winding comprises a plurality of coils disposed adjacent said primary windings on said core.

Signed at New York city, this 2nd day of February, 1924.

CHARLES B. WATERS.

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